Can I change the DS1307's crystal

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winchell chung
 
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Can I change the DS1307's crystal

Post by winchell chung »

I was admiring the DS1307 Real Time Clock breakout board kit. The crystal is a 32.768 KHz crystal.
Am I correct in assuming that if I swap the crystal with one of a different value, it will affect the clock speed?

What I am trying to do is make a sidereal clock, which is used in astronomy. Sidereal time runs faster than BANNED Mean Time by about 3 minutes and 56 seconds per day. Which in theory means if I swap the 32.768 KHz crystal with a 32.858 KHz crystal the DS1307 will run sidereal time.

Assuming I can find such crystals, is it that easy, or are additional electronics required?

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adafruit_support_bill
 
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Re: Can I change the DS1307's crystal

Post by adafruit_support_bill »

Interesting topic. Maxim has an app-note on crystal selection - if you could find one at that frequency.
http://www.maximintegrated.com/en/app-n ... .mvp/id/58
Here is one approach to the problem: http://www.jimbo.net/circuitfarm/2010/07/sidereal-time/

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winchell chung
 
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Re: Can I change the DS1307's crystal

Post by winchell chung »

Thanks for the links!

Sidereal clocks have a very limited market, all of it astronomy related. Generally only in astronomical clocks and telescope tracking motors.

I just so happen to have a couple of specialty crystals of the correct values. Though your jumbo.net link is very interesting

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